"Still Valley" is the eleventh episode of the third season of The Twilight Zone, and was first broadcast in November of 1961. It was based on a short story by Manly Wade Wellman, with a teleplay by Rod Serling. It starred Gary Merill as Sgt. Paradine, and Vaughn Taylor as an old sorcerer named Teague.
In the year 1863, Sgt. Paradine is a confederate soldier on a reconaissance mission in Virginia, where he is sent to check on a union advance company. When he finds the company, it is frozen totally in place. He comes across an old man named Teague who says that he has a magic spell capable of freezing soldiers in place: a spell that he can not use because he is about to die. Falling dead, Teague goes back to his camp with the book, and must decide whether to call on the power of the devil in order to win the war.
The original story isn't by Rod Serling, but it follows a set-up that we have seen earlier, as far back as the first episode "Where is Everybody?", where a soldier is exploring a town where he is the only person. More specifically, "Elegy" had a town of frozen people. "King Nine Will Not Return" and "Two" also had soldiers in deserted areas, trying to figure out what was going on around them. Solitude and war are themes that Serling liked, very apparently. I can't tell where this episode went with the themes: it could be that the moral dilemma of using dark powers to win a war was an allegory for nuclear weapons and The Cold War, or it could be that the story is more of a non-topical folk story.
As I mentioned in my review for "The Passerby", the usage of The Civil War seems to be non-topical, whereas today it might bring up regionalistic tones. I do find it difficult to believe that using the power of the devil would provide much of a problem for the confederacy, since in my view it is the devil they were fighting for in the first place. I do also find it ironic that the actor who played Sgt. Paradine, Gary Merill, was a civil rights activist who would, several years after this episode aired, march with Martin Luther King, Jr. on Montgomery.